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<title>EVP_SIGNATURE-ED25519</title>
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<ul id="index">
  <li><a href="#NAME">NAME</a></li>
  <li><a href="#DESCRIPTION">DESCRIPTION</a>
    <ul>
      <li><a href="#ED25519-and-ED448-Signature-Parameters">ED25519 and ED448 Signature Parameters</a></li>
    </ul>
  </li>
  <li><a href="#NOTES">NOTES</a></li>
  <li><a href="#EXAMPLES">EXAMPLES</a></li>
  <li><a href="#SEE-ALSO">SEE ALSO</a></li>
  <li><a href="#COPYRIGHT">COPYRIGHT</a></li>
</ul>

<h1 id="NAME">NAME</h1>

<p>EVP_SIGNATURE-ED25519, EVP_SIGNATURE-ED448, Ed25519, Ed448 - EVP_PKEY Ed25519 and Ed448 support</p>

<h1 id="DESCRIPTION">DESCRIPTION</h1>

<p>The <b>Ed25519</b> and <b>Ed448</b> EVP_PKEY implementation supports key generation, one-shot digest sign and digest verify using PureEdDSA and <b>Ed25519</b> or <b>Ed448</b> (see RFC8032). It has associated private and public key formats compatible with RFC 8410.</p>

<h2 id="ED25519-and-ED448-Signature-Parameters">ED25519 and ED448 Signature Parameters</h2>

<p>No additional parameters can be set during one-shot signing or verification. In particular, because PureEdDSA is used, a digest must <b>NOT</b> be specified when signing or verifying. See <a href="../man7/EVP_PKEY-X25519.html">EVP_PKEY-X25519(7)</a> for information related to <b>X25519</b> and <b>X448</b> keys.</p>

<p>The following signature parameters can be retrieved using EVP_PKEY_CTX_get_params().</p>

<dl>

<dt id="algorithm-id-OSSL_SIGNATURE_PARAM_ALGORITHM_ID-octet-string">&quot;algorithm-id&quot; (<b>OSSL_SIGNATURE_PARAM_ALGORITHM_ID</b>) &lt;octet string&gt;</dt>
<dd>

<p>The parameters are described in <a href="../man7/provider-signature.html">provider-signature(7)</a>.</p>

</dd>
</dl>

<h1 id="NOTES">NOTES</h1>

<p>The PureEdDSA algorithm does not support the streaming mechanism of other signature algorithms using, for example, EVP_DigestUpdate(). The message to sign or verify must be passed using the one-shot EVP_DigestSign() and EVP_DigestVerify() functions.</p>

<p>When calling EVP_DigestSignInit() or EVP_DigestVerifyInit(), the digest <i>type</i> parameter <b>MUST</b> be set to NULL.</p>

<p>Applications wishing to sign certificates (or other structures such as CRLs or certificate requests) using Ed25519 or Ed448 can either use X509_sign() or X509_sign_ctx() in the usual way.</p>

<p>Ed25519 or Ed448 private keys can be set directly using <a href="../man3/EVP_PKEY_new_raw_private_key.html">EVP_PKEY_new_raw_private_key(3)</a> or loaded from a PKCS#8 private key file using <a href="../man3/PEM_read_bio_PrivateKey.html">PEM_read_bio_PrivateKey(3)</a> (or similar function). Completely new keys can also be generated (see the example below). Setting a private key also sets the associated public key.</p>

<p>Ed25519 or Ed448 public keys can be set directly using <a href="../man3/EVP_PKEY_new_raw_public_key.html">EVP_PKEY_new_raw_public_key(3)</a> or loaded from a SubjectPublicKeyInfo structure in a PEM file using <a href="../man3/PEM_read_bio_PUBKEY.html">PEM_read_bio_PUBKEY(3)</a> (or similar function).</p>

<p>Ed25519 and Ed448 can be tested with the <a href="../man1/openssl-speed.html">openssl-speed(1)</a> application since version 1.1.1. Valid algorithm names are <b>ed25519</b>, <b>ed448</b> and <b>eddsa</b>. If <b>eddsa</b> is specified, then both Ed25519 and Ed448 are benchmarked.</p>

<h1 id="EXAMPLES">EXAMPLES</h1>

<p>To sign a message using a ED25519 or ED448 key:</p>

<pre><code>    void do_sign(EVP_PKEY *ed_key, unsigned char *msg, size_t msg_len)
    {
        size_t sig_len;
        unsigned char *sig = NULL;
        EVP_MD_CTX *md_ctx = EVP_MD_CTX_new();

        EVP_DigestSignInit(md_ctx, NULL, NULL, NULL, ed_key);
        /* Calculate the requires size for the signature by passing a NULL buffer */
        EVP_DigestSign(md_ctx, NULL, &amp;sig_len, msg, msg_len);
        sig = OPENSSL_zalloc(sig_len);

        EVP_DigestSign(md_ctx, sig, &amp;sig_len, msg, msg_len);
        ...
        OPENSSL_free(sig);
        EVP_MD_CTX_free(md_ctx);
    }</code></pre>

<h1 id="SEE-ALSO">SEE ALSO</h1>

<p><a href="../man7/EVP_PKEY-X25519.html">EVP_PKEY-X25519(7)</a> <a href="../man7/provider-signature.html">provider-signature(7)</a>, <a href="../man3/EVP_DigestSignInit.html">EVP_DigestSignInit(3)</a>, <a href="../man3/EVP_DigestVerifyInit.html">EVP_DigestVerifyInit(3)</a>,</p>

<h1 id="COPYRIGHT">COPYRIGHT</h1>

<p>Copyright 2017-2021 The OpenSSL Project Authors. All Rights Reserved.</p>

<p>Licensed under the Apache License 2.0 (the &quot;License&quot;). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>


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